Large families are the cornerstone of success for human genetics studies. Large families residing in Utah have had a particularly important historic impact on the field of human genetics research. The mapping of disease genes has been facilitated by the creation of comprehensive human genetic maps that have been developed utilizing DNA from large Utah families. These maps were created by studying the segregation of DNA polymorphisms in large, three-generation families from Utah. These families are the point of departure for this project. The first aim of this project is to collect phenotypic data from these families. Forty-seven families who originally participate in the mapping project will be revisited. Each is comprised of eight to eighteen members, who will undergo both blood drawing and physical testing at the GCRC over a ten-hour period on a Saturday. Fifteen families have already undergone this comprehensive testing during a pilot phase of the study. A second aim of the study is to create an information database of the phenotypic and genotypic data collected. The investigators plan to make this information available not only to scientists at the University of Utah but also to those outside of the state who wish to use the phenotype-genotype correlations identified to map genes responsible for common human traits and common diseases. The third aim is to carry out genetic linkage analyses of inherited human traits of interest.